.app{
	width: 100%;
	height: 100vh;
	background-color: #ffffff;
	position: relative;
	display: flex;
	justify-content: center;
	align-items: center;
}
.btn31{
	width: 190px;
	height: 42px;
	cursor: pointer;
	border: none;
	border-radius: 4px;
	background-color: #333;
	font-size: 16px;
	font-weight: 700;
	color: #fff;
	transition: 0.3s;
}
.btn31:hover{
	background-color: #3185fa;
}
.btn31:active{
	animation: btn31-eff 3s linear infinite;
}
@keyframes btn31-eff{
	0%{
		box-shadow: 0 0 2px #3185fa;
	}
	50%{
		box-shadow: 0 0 40px #3185fa;
	}
	100%{
		box-shadow: 0 0 2px #3185fa;
	}
}